High-sensitivity terahertz metasurface sensor for refractive index and methane detection with advanced material integration

In the present study, we have considered a highly sensitive terahertz metasurface-based sensor for detecting minute changes in refractive index, in addition to the changes in methane concentrations as well. By using COMSOL Multiphysics and the Finite Element Method, we have investigated the numerical findings. Meanwhile, the sensor achieves sensitivities of 600 GHz/RIU for general gases and 294 GHz/RIU for methane at the optimum values of some different parameters, including graphene’s chemical potential and the angle of incidence. In addition, the numerical findings demonstrate the emergence of multiple absorption bands with transmission minima between 75.687% and 79.657% and frequency shifts that correlate linearly with refractive index changes (R2 = 92.63% for various gases; R2 = 99.848% for methane). In addition, machine learning optimization using the Extra-Trees Regressor enhances predictive performance, achieving R2 values between 90% and 95%. This work offers a CMOS-compatible, high-sensitivity platform for advanced environmental monitoring and safety applications.